1. Field of the Invention
The present invention relates to an operative hinge, and more particularly to an operative hinge suitable for use with an opening/closing body such as a seat and seat lid of a toilet bowl.
2. Description of the Prior Art
Various types of operative hinges for use with a seat and seat lid of a toilet bowl have been proposed so fax. Typical ones of such hinges include a combination of a shaft to support thereon the toilet seat and lid to be pivotable for opening or closing, with a cam mechanism incorporating a compression spring to act on the shaft, a combination of a rotating shaft and a torsion spring which acts to cancel a torque of the shaft being rotated in a predetermined direction, a combination of a rotating shaft and a rotating hydraulic damper, or a similar combination
The combination of a rotating shaft with a cam mechanism incorporating a compression spring to act on the shaft is advantageous in that a matching can be easily be attained between a torque generated when the seat and lid are operated and an angular moment of the seat and lid. For a large rotating torque, however, the entire structure of the operative hinge should be designed larger.
The combination of a rotating with only a torsion spring acting on the shaft has an advantageous in that a small structure can create a large rotating torque. Since it creates a rotating torque which will increase and decrease linearly, however, no easy matching is possible between the rotating torque and an angular moment of the seat and lid which will depict a sine curve, and it is difficult to elaborately fit the movement of the seat and lid as necessary to the rotating torque and also to appropriately control the movement of the seat and lid in each of the operating steps.
Further, the combination of a rotating shaft with only a rotating hydraulic damper is advantageous in that it is difficult to elaborately fit the moment of the seat and lid as necessary to the rotating torque and appropriately control the movement of the seat and lid in each of the operating steps, and that the seat and lid being opened or closed cannot easily be stopped and halted in au intermediate angular position and braked at a predetermined angular position the seat and lid have reached during each of the operating strokes, for example.